sink

The initial reference count of a newly created ParamSpec is 1, even though no one has explicitly called @ref on it yet.

So the initial reference count is flagged as "floating", until someone calls `g_param_spec_ref (pspec); g_param_spec_sink (pspec);` in sequence on it, taking over the initial reference count (thus ending up with a this that has a reference count of 1 still, but is not flagged "floating" anymore).

Parameters: